The hot air, steam bath, and hot compress have the advantage over the mere irritant derivatives that their action is from first to last soothing and free from all risk of inducing sympathetic irritation and yet as derivatives they are eminently efficient. Next to them in safety and efficacy comes dry cupping.
The irritant derivatives are often the most valuable, but must be used with great judgment. They are always dangerous when the pleural inflammation runs very high and when the local irritation and suffering are specially acute. Under such circumstances it is usually desirable to adopt other measures to moderate the severity of the inflammation, and to fall back on baths, compresses and cups until the irritation is alleviated before vegetable or animal vesicants are resorted to. In acute and severe attacks these latter are especially applicable to the early stages before the inflammation has been fully formed, or after the stage of free effusion has set in.
With high fever and no benefit from hot local applications, cold irrigation or refrigerant compresses to the walls of the chest, have proved useful, but considering the rôle filled by cold in causation and the suggested relation between pleurisy and rheumatism this is not to be followed as a general practice.
If the patient has been a hearty feeder and if there is evident costiveness a purgative (aloes or sulphate of soda) is often desirable at the outset, but if the disease is of a low type this is always dangerous, owing to susceptibility of the intestinal mucosa and it is safer to correct constipation by injections or at most by a pint of olive oil.
When the suffering is very acute and is aggravating the fever, a hypodermic injection of morphine will often greatly relieve and even favor a revulsion of blood toward the skin, but as it tends to suppress the action of both bowels and kidneys it should be avoided unless it seems absolutely necessary, and above all it should not be given by the stomach. Cocaine hypodermically may be used to relieve pain.
Both fever and suffering can sometimes be greatly relieved by large doses (2 drachms 3 or 4 times daily) of salicylate of soda, which again suggests a close relation of the disease to rheumatism. Acetanilid or phenacetin may be used to fill the same indication.
Next come the questions of alkaline and diuretic treatment. Some cases do well if given nitrate of potash freely in the drinking water. Some prefer the alkaline diuretics, such as acetate of potash or ammonia, bicarbonate of potash or soda, biborate of soda, or the vegetable diuretics such as colchicum, squills, etc. Fraënkel found that, while comparatively ineffective alone, these proved most efficient (in man) when combined with cinchona or other bitter. The hint should be useful to the veterinarian. Diuretics in the stage of effusion should be pushed as far as the strength of the patient will warrant.
Friedberger and Fröhner recommend pilocarpin, and no agent produces an equal secretion from the natural emunctories and an equal tendency to reabsorption. It is however so profoundly exhausting that it must be used with the greatest judgment and caution.
Digitalis has often an excellent effect. Though not primarily a diuretic, it is a powerful tonic of the heart and circulation, and by increasing the blood tension it usually produces a free flow of urine. In combination with the diuretic salts it may be used from the first but it is especially valuable, after effusion and when attention must be given mainly to securing reabsorption. Care is demanded that we avoid its cumulative action, and in place of continuous large doses, a strong infusion applied over the loins will sometimes have a good effect. It may also be combined with bitters and even with ferruginous tonics in the advanced stages.
In combination with neutral salts and digitalis, iodide of potassium would seem to be indicated. Results however do not show a great superiority to other diuretics in favoring absorption.